1. Field of the Invention
This invention relates generally to a method and apparatus for selectively recovering or collecting scrap metal having selected properties. More particularly, the present invention relates to a method and apparatus for segregating non-magnetic metal containers such as aluminum containers or cans from other deposited materials and for compensating depositors of such scrap metal based on the weight of the scrap metal so collected.
2. Description of the Related Art
Non-reusable, non-returnable metal containers or cans of various types are currently used to package many different types of foods and beverages and have become part of the American way of life. Many products, particularly soft drinks and malt cereal beverages, are provided to the consumer in metal cans. Aluminum cans or containers provide particular advantages because of the relatively light weight of aluminum. Aluminum's resistance to corrosion and food contamination is also an important characteristic, as is the fact that aluminum leaves no "tinny" taste. A further advantage of aluminum is that aluminum cans or lids can be provided with tear tabs, press tabs or pop tops making them even more convenient for use by the consumer and eliminating the need for can openers and the like. More than 60 billion aluminum cans are used each year. The growth of this market is 8 to 10 percent per year. Currently about 53 percent of aluminum cans are being recycled.
With rapid increase in the use of non-reusable, non-returnable metal containers, the problem of littering has become quite serious as anyone driving on America's highways can attest. Unfortunately, many consumers carelessly discard metal cans blighting the countryside, spoiling the scenery and costing governments large sums of money for clean-up and the like. Consumer groups, beverage industry groups, governmental groups and others have attempted to meet this problem by establishing recycling centers which compensate individuals for aluminum containers brought back to the recycling center. The returned aluminum cans can be recovered and refabricated into new cans thus reducing litter, saving about 95 percent of the energy spend in refining aluminum ore, and conserving aluminum metal as a natural resource. However, even the establishment of recycling centers has not completely alleviated the problem as many people still carelessly throw away or discard used containers.
Part of the problem lay in the fact that it was often necessary for the consumer to collect or save the cans for a long period of time before returning them to the recycling center. Since the price paid at the recycling center did not always compensate the driver for the cost of transportation unless a large number of cans were saved, saving or storing the cans between trips to the recycling center often became messy and sloppy as some liquid always managed to remain in the cans and somehow leaked through the storage bags, boxes or the like drawing flies and other insects, as well as causing an unsightly mess, stains, sticky spots, and the like.
Further attempts were made at having a return center closer to the consumer, and many grocery stores began accepting aluminum cans. However, the grocery stores ran into the same problems of leakage, storage space, mess, and man power required to implement the system, and hence the price payed for the recycled aluminum cans was less than it would otherwise have been.
Therefore, a need existed for a method and apparatus for receiving and processing metal containers and particularly aluminum cans which would be convenient to the consumer and provide the necessary incentives so that the consumers would be encouraged to collect and return empty containers in any given amount. Preferably, such apparatus would be located throughout the community at convenient locations such as parking lots and shopping malls and the like and would operate unattended to reduce cost and enable the collection apparatus or facility to pay fair compensation for aluminum containers and the like.
The first significant attempt to solve the problem is disclosed is U.S. Pat. No. Re. 27,643 issued to Joseph D. Myers. This patent discloses a method and apparatus for the collection of metal containers which automatically dispenses tokens for each non-magnetic container stored. The system, while effective, does not separate selected aluminum containers from general refuge and trash and extraneous material can cause the machine to jam or become inoperative. Further, compensation or tokens are dispensed in response to a county of non-magnetic containers rather than in relation to the weight of the selected metal recovered by the apparatus. There are many disadvantages to this type of approach.
The next step in the evolution of systems for selectively collecting scrap metal are best represented by U.S. Pat. Nos. 4,179,018 and 4,257,511 which issued to John H. Miller. These patents disclose method and apparatus in which non-returnable aluminum cans used to package soft drinks and malt cereal beverages are segregated from other material such as tin-plated steel cans that are deposited in the apparatus. A start button or switch is pushed by the depositor to start the operation of the apparatus and the deposited materials are conveyed by a conveyor belt to a magnetic separation portion of the apparatus to separate magnetic, ferrous materials such as tin-plated steel cans from the non-magnetic material and store the ferrous materials in a storage bin. However, non-magnetic materials are collected at the bottom of a pneumatic classifier conveyor which transports the aluminum, non-ferrous metal containers to a crusher. The materials so transported are crushed and weighed. After weighing, the crushed aluminum cans are conveyed by a pneumatic stacker conveyor and deposited into an inclined storage location at the top of the apparatus.
The apparatus of Miller is provided with a compensation dispenser which dipenses or disperses coins, tokens and other symbols of value, the amount of which is determined by the weight of the non-ferrous materials that pass through the crusher and are weighed by the weighing means during operation of the collection apparatus. This type of apparatus is designed to be used in an unattended mode and is frequently placed in parking lots or shopping centers, shopping malls, and the like where it is easy for persons, customers and consumers who patronize the retail stores to dispose of their collected aluminum cans while being paid therefor.
The recovered aluminum from this source saves energy and raw materials while simultaneously reducing the problems associated with the disposing of such cans after their contents have been consumed and greatly alleviating the litter problem. While the present price of tin-plated steel cans makes it almost impossible to compensate for them, their collection is of some intrinsic value insofar as cleaning up the environment is concerned. Notwithstanding, a depositor is notified that he will not be compensated for a tin-plated steel can, at least at the present time.
The next step in the evolution of selective scrap metal collection systems is set forth in U.S. Pat. No. 4,402,391 issued Sept. 6, 1983 and invented by the inventors of the present invention. This patent describes an improved method and apparatus for metal collection and particularly for collecting selective metals such as aluminum. The apparatus includes means for performing diagnostics through the use of a smart digital controller. The teachings of this application are hereby incorporated by reference herein. The apparatus disclosed therein had several limitations. First, field results have indicated that the apparatus does not adequately weigh the deposited material under all conditions. It has been shown that under the best conditions, the apparatus set forth in the Miller patent will weigh an accuracy of no greater than 95 percent; however, many weights and measure codes require a greater accuracy such as at least 98 percent. Furthermore, field failure of the scale dump solenoid has resulted in a failure to compensate a depositor for cans deposited in some instances. The existing system requires a great deal of service and maintenance and throughput is somewhat limited. Furthermore, the existing systems do not permit the addition of new features without relatively complex changes in the components within the existing controllers.
Untrained service personnel tend to operate the system in such a manner as to damage the solid state relays and there is a tendency on the part of maintenance personnel to calibrate the system even when calibration is not required. Furthermore, the system had no mechanism for ensuring that the payout was equal to the advertised price per pound and an additional problem detrimental to the total operation of the system is that it can accept non-metallic objects which are lighter than cans or within the general weight-size profile of an aluminum can, such as milk cartons, small plastic bottles and the like which can be readily processed and payed for by the present apparatus.
The next step in the evolution of selective scrap metal collection systems was disclosed in U.S. Ser. No. 463,573, filed Feb. 2, 1983 now U.S. Pat. No. 4,499,984 by the present inventors and assigned to the assignee of the present invention. This patent teaches an improved metal collection apparatus for collecting selective metal such as aluminum primarily in the form of used aluminum cans and for compensating depositors of such metal cans based on the weight of the selected metal collected. The collecting apparatus is free-standing and is designed to function unattended. The apparatus is provided with a hopper into which depositors place material, including aluminum cans, which the machine is designed to collect, the depositor then pushes the start button in the vicinity of the hopper to initiate operation of the apparatus. The deposited materials are carried from the hopper to a classifier by means of an endless conveyor belt and the classifier segregates magnetic or ferrous material from the non-magnetic materials. A pneumatic conveyor conveys aluminum cans to a crusher. The more dense non-magnetic materials collect in the bottom of the bin provided in the pneumatic conveyor and the aluminum materials is conveyed by the conveyor of the classifier to the crusher where the material is crushed so as to be more compact and to occupy significantly less space when stored. After passing through the crusher, the crushed material is weighed and its weight noted. The crushed material is then dumped into a stacker conveyor which transports the crushed aluminum cans to a storage bin in which they are stored until forwarded to a recycling plant. A digital electronic controller is provided to control the energization of the motors that drive the conveyors and the crusher and to provide power to the classifier. The weigher produces an analog signal that is digitized by an analog-to-digital converter, causes the compensation dispenser to dispense or disperse an appropriate amount of compensation in the form of coins or possibly even tokens. The apparatus is provided with motor alarm circuits which produce an alarm signal if any one of the motors is not running properly when energized, and the coin dispensing apparatus will produce an alarm signal if no coins or tokens are available to be dispensed. A detector is provided which produces an alarm signal each time a piece of magnetic material, such as a steel can or tin-plated steel can, is segregated from the materials deposited. An alarm signal will also be produced when the container or receptacle which receives these materials is full. Another detector is provided which produces an alarm signal if a jam occurs in the classifier conveyor since such a jam will prevent aluminum cans from being fed to the crusher. The electronic controller also includes circuit means for automatic calibration of the weighing system which is used to measure the weight of the aluminum cans deposited therein to assure that it is accurately weighing the material dumped. The digital electronic controller adjusts the set gain of the system such that the output of the weighing system is well within the range of the analog-to-digital converter. The autocalibration is updated continuously between cycles which results in optimum performance of the weighing system. In addition to this calibration, the load cell is initialized with a load-to-voltage-out reference resistor. Thus, replacement of the load cell or controller, changes in temperature, or variations in the power supply will not effect system accuracy. In addition to these features, the system is designed to reduce service in the field to an absolute minimum and built-in test features allow for easy and rapid troubleshooting. The system has an improved cycle time which is accompanied by increasing the weight of the bucket before stopping from 0.75 pounds to 1.5 pounds. Thus, the throughput of the apparatus is increased from 150-200 pounds per hour to 300-400 pounds per hour. To facilitate service and operation, retest features are incorporated which periodically reject all failed conditions. This system is capable of detecting operation of the scale-dump solenoid and the controller uses its knowledge of weight to detect whether the scale door is open. Other features include apparatus relating to the security of the money paid out such that the compensation rate is not set as previously done, with thumb wheel switches but in a non-volatile memory which provides an account of money and poundage and remembers the quantities even if power fails or is turned off. All solid state output devices are protected by short circuit protection circuitry to protect driver devices, and the error rate in weighing is less than one percent due to altering the sequence of operation and utilizing an improved bucket arrangement.
The next step in the evolutionary process is described in U.S. patent application Ser. No. 518,148, filed July 28, 1983, now U.S. Pat. No. 4,597,487. Many of the prior systems, however, still suffer from one or more shortcomings. Some do not provide for collection of re-claimable material using an adjustable but accurate pay out means for compensation which includes a customer display of both the weight of the collected re-claimable material and the money paid out. Prior systems do not generally provide a means for separating out ferrous materials magnetically and then separating heavy's and non-metals from non-ferrous metallic materials. Prior systems still generally pay for small plastic bottles and many glass and paper products. Prior systems do not generally display the weight of the contents of the material to the operator or depositor while he is putting the material into the apparatus and none appears to provide an accuracy good to 0.01 pounds. The prior systems do not have internal counters or memories that keep track of the poundage and the compensation to the nearest hundredth of a pound and the nearest penny for compensation, and none of the systems of the prior system provide any real self-testing or auto test modes of operation to assist in troubleshooting and the like. Most do not have an error re-test feature to minimize down time, and a second metal detector to determine the presence of non-ferrous metallic materials. No prior systems use of a heavy detector whose operation depends on how far a door or platform is moved or displaced when material falls on it. No prior system pays only in quarters or the largest coin denomination until the end of the operation when it pays the remaining compensation in smaller coins, as required. None has the ability to stop the crusher to prevent cans from coming into the bucket during the weighing operation and to provide an apparatus that has a continuous input feed. None of the present devices are self-adjusting so that the operator or depositor never has to make any adjustment such as zeroing, calibration or metal sensing. A need was therefore felt for a scrap metal collection system similar to the system described in copending U.S. patent application Ser. No. 518,148 filed on July 28, 1983 now U.S. Pat. No. 4,597,487 and invented by the inventors of the present U.S. patent application.